Mizzen sheet bridle replacement w/ dyneema

[DenisHeinrichs]

I own a whitby 42 ketch. One of the curious items on the whitby is the bridle for the mizzen sheet. It looks like this (this is not from my boat): https://www.whitbybrewersailboats.co...zzenBridle.jpg


I would like to replace it with dyneema, as this is fairly old, and can make a lot of noise (our master stateroom is below this).

I know how to splice loops into the ends of it, but what do I do about the loop in the middle? Do I even need the loop or just let it slide through the end of the shackle? Also, what size of dyneema should I be using in this application. The mizzen sail on the whitby is about 175 sq ft.


Thanks
Denis

[Dsanduril]

There are a couple of ways to do a middle eye, but is it worth the bother? How about just making two equal-length strops with an eye in both ends? Quick and easy.

For strength 1/4” (6mm) would be more than sufficient, UV protected or stabilized preferred.

You could probably luggage tag each strop to the padeye, eliminating the shackle and a source of noise.

[DenisHeinrichs]

Great idea...and simple!



I am hitting myself for not thinking of this


This is what I love about CF!!


Just for curiosity sake...what are the ways to do a middle eye? Is there a particular method I can google?


Thanks
Denis

[thinwater]

The correct way to do this is with two separate legs with an eye in each end. There is no reason to make a Y and it will be weaker than two separate legs.


Some people will make a middle eye with a Brummel lock, but it makes a considerable weak spot, no better than a knot. There have been high profile failures of this construction.

[Dsanduril]

Thinwater beat me to it. A couple of Brummels would be the “standard” way, but these really only work reasonably well when both legs are loaded equally. With only one side loaded all the tension ends up on one of those locks.

One of the butterfly style knots would work, I’d defer to the gurus here for which would be best. But it will weaken the whole thing (OTOH this will probably be way overstrength to begin with unless you go with really tiny Dyneema).

Seaworthy Lass here on CF has a basket weave strop for holding a low friction ring, I’d suspect that could be modified to make an eye in the middle, but I’d have to look at it.

[Breaking Waves]

There are two splices that would get you to around 80% strength - so rather better than a knot but less good than the two separate legs.

There is a theoretical limitation, related to the stress riser where the one lazy leg exits the splice from the loaded leg which means that it is hard to get past 80% with conventional splicing approaches.

I am decently confident there is an 'insert extra tapered cord' approach which would be 100% - I could envision several ways to do this, but have never directly specifically tested any of them.

You could use what is called a 'cut splice' doing tapered tucks . . . but if you are going there you might as well just make two separate legs.

Machine sewing could get you to near 100%, but is hard to do DIY.

[Hudson Force]

I would consider something like the Endura line that has a UV protection sleeve over the Dyneema core. I used this for some of the rigging with my ketch,- 'suited me well.